Structure and plating method of thin film magnetic head and magnetic storage apparatus

ABSTRACT

A material for magnetic pole for attaining a writing head generating an intense recording magnetic field, and a structure and a manufacturing method therefor. The thin film magnetic head includes a magnetic pole layer having a plated magnetic layer containing Co, Ni and Fe formed on a plated underlayer of a sputtered magnetic layer containing Co, Ni and Fe. The CoNiFe magnetic layer having a composition: 40 wt %≦Co≦70 wt %, 10 wt %≦Ni≦25 wt % and 10 wt %≦Fe≦30 wt % and a peak intensity ratio in the X-ray diffraction of I(200)/I(111)≧0.5 and I(110)/I(111)≧1 (defining peak intensities for the face-centered cubic fcc (111) face, fcc (200) face and the body-centered cubic bcc (119) face as: I(111), I(200), I(110)).

PRIORITY TO FOREIGN APPLICATIONS

This application is a Divisional of U.S. Ser. No. 09/917,892 filed Jul.31, 2001, now U.S. Pat. No. 6,723,449. Priority is claimed based on U.S.Ser. No. 09/917,892 filed on Jul. 31, 2001, which claims the prioritydate of Japanese patent application 2000-377989 filed on Dec. 7, 2000.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a thin film magnetic head used forrecording/reproduction in a magnetic disk storage apparatus, amanufacturing method therefor, and a magnetic disk storage apparatus anddisk array system. in which to mount the thin film magnetic head.

2. Description of the Background

Along with an increase in the recording density of magnetic disk storageapparatuses, the coercive force of the recording media has also beenincreased. A need has been recognized in the art to provide a materialhaving a high saturation magnetic flux density (Bs) that is capable ofproducing a magnetic field strong enough to write into a high coercivemedium for the magnetic core material or writing heads.

Materials having a high saturation magnetic flux density include CoNiFe(Bs>1.7 T) which has a higher Bs than Ni₄₅Fe₅₅ that is currently used asthe magnetic core material (Bs: 1.6 T) as described in JP-A-89422/1994,JP-A-241503/1996, JP-A-346202/1994 and JP-A-3489/1995. Further, JapanesePatent Publication No. 2821456 discloses a method of preparing a platedlayer with a high Bs using a bath without the addition of saccharinesodium in the plating solution composition.

To attaining a magnetic disk storage apparatus with high recordingdensity, it may be necessary to use a layer forming technique capable ofstably forming a magnetic core with an increased thickness forgenerating a more intense magnetic field. The technique includes the useof a material with a high saturation magnetic flux density (Bs) capableof producing a sufficient magnetic field to write into a high coerciveforce medium.

As described in Japanese Patent Publication No. 2821456, the Co—Ni—Fesoft magnetic material layer prepared from a bath that does not containa stress relieving agent has a Bs of at least 1.9 T and a Hch of no morethan 2.5 Oe. Because since the stress of the plated layer is large,peeling may ensure in a formed layer with a thickness greater thenapproximately 2.0 μm, making the layer formation difficult.

Further, as described in JP-A-346202/1994, the soft magnetic Co—Ni—Fematerial layer prepared from a bath containing a stress relieving agentmay provide a layer with a low coercive force of approximately Hch=0.4Oe. However, assuming the peak intensities at fcc (111) face, fcc (200)face and bcc (110) face in the X-ray diffraction as I(111), I(200) andI(110), respectively, such a layer could not be obtained unless asubstantially face-centered cubic system was formed having a peakintensity ratio of 0.1≦I(200)/I(111)≦0.2 and annealing was applied afterthe formation of the layer. Further, unevenness may increase in thesurface shape of a layer if the layer composition is deviated in aregion containing a slight amount of body-centered cubics in theface-centered cubics, which results in clouding and an inability toobtain a gloss layer.

As can be seen from the conventional applications described above, it isdifficult to stably mass produce magnetic heads having high saturationmagnetic flux density capable of producing sufficient magnetic fieldswhich correspond to a high recording density.

SUMMARY OF THE INVENTION

To address one or more of the above limitations in the conventionaldevices, in accordance with at least one preferred embodiment of thepresent invention, a magnetic layer containing Co, Ni and Fe is formedby a sputtering method as a plated underlayer and a magnetic layercontaining Co, Ni and Fe is formed on the plated underlayer by anelectroplating method to form a magnetic pole layer. In accordance withthis invention, Co, Ni and Fe are preferably present as: 40 wt %≦Co≦70wt %; 10 wt %≦Ni≦25 wt %; and 10 wt %≦Fe≦30 wt % in the sputtered layeras the plated layer and the plated underlayer. Further, in accordancewith this invention, only bcc is preferably observed for the sputterlayer as the plated underlayer under X-ray diffraction, and the peakintensity ratio is: I(200)/I(111)≧0.5 and I(110)/I(111)≧1, when definingpeak intensities in fcc (111) face, fcc (200) face, and bcc (110) facein the X-ray diffractiometry for the plated layer as I(111), I(200) andI(110), respectively.

A small peak intensity ratio I(200)/I(111), I(110)/I(111) means thatcrystals are intensely oriented to the face-centered cubic fcc (111)face. The films which are substantially fcc described inJP-A-34020/1994, Japanese Patent Publication No. 2821456 belong to thiscase. However, since the present invention preferably uses a softmagnetic thin film in which the constitutional ratio of theface-centered cubic system and body-centered cubic system (ratio for thebody-centered cubic system and the face-centered cubic system in themagnetic layer) is: 40%≦body-centered cubic system≦80% and20%≦face-centered cubic system≦60%, and face-centered cubicsystem+body-centered cubic system is 100%, it may suffice that the peakintensity ratio is I(200)/I(111)≧0.5 and I(110)/I(111)≧1. In addition,since a lot of body-centered cubic system is contained in the layer, thedeviation in the layer composition, if any, preferably has no effect onthe surface shape of the layer, and a glossy layer can be preparedstably as in this invention.

Additionally, by using a CoNiFe layer also for the plated underlayer,the crystallinity of the plated layer is enhanced, and thecrystallographic orientation can be controlled more easily with thepresent invention compared to the conventional applications. When theCoNiFe layer is used partially or entirely for the upper magnetic poleof the writing head, since the underlayer is situated on the side of themagnetic gap relative to the lower magnetic pole, the saturationmagnetic flux of the underlayer, when using a permalloy layer forinstance, is lower than that of the plated layer which decreases thewriting magnetic field.

On the contrary, when the CoNiFe layer is used according to thisinvention, it preferably has a saturation magnetic flux density equal toor greater than the plated layer to improve the characteristics of thehead. When different kinds of metals are laminated, they may lead tocell reactions that may possibly corrode the CoNiFe plated layer, butsuch corrosion may be avoided when the CoNiFe layer is used also for theunderlayer, as in at least one preferred embodiment of the presentinvention.

The CoNiFe magnetic thin film of the present invention may form a CoNiFemagnetic plated layer containing saccharine sodium by preparing thelayer from a plating bath containing saccharine sodium as a stressrelieving agent and conducting the electroplating under the followingpreferred conditions: a bath temperature within the range from 25° C. to35° C.; a current density from 3 to 12 mA/cm²; and a pH value fromapproximately 3.2 to 4.0. A thick layer of at least 3 μm may also beformed by conducting plating under the plating conditions describedabove.

Further, the magnetic characteristics of the soft magnetic layerobtained according to preferred embodiments of the present invention mayhave: a saturation magnetic flux density Bs of: 17500 gauss≦Bs<20000gauss; a coercive force in the difficult axis direction Hch of: Hch<1.50Oe; and a saturation magnetic flux density of the underlayer that isgreater than the Bs of the plated layer. While JP-A-3489/1995 describesthat the coercive force is increased at the peak intensity ratio:I(200)/I(111)≧0.2, a coercive force of Hch<1.5 Oe is preferably attainedby the present invention thus avoiding one or more of the conventionaldifficulties.

Further, in a recording/reproducing separation type thin film magnetichead using a magnetoresistive element for the reading device and aninduction type magnetic head for the writing device, recording may bepossible to a recording medium with a coercive force of at least 4000 Oeby using the soft magnetic CoNiFe layer partially or entirely as thelower and upper magnetic cores of the writing head according to thepresent invention.

Additional objects, features and/or advantages of the invention willappear more fully from the following description of the invention,drawings, and attached claims.

BRIEF DESCRIPTION OF THE DRAWINGS

To enable the present invention to be more clearly understood andreadily practiced, the present invention will be described inconjunction with the following figures, wherein like referencecharacters designate the same or similar elements, which figures areincorporated into and constitute a part of the specification, wherein:

FIG. 1 illustrates a process flow for a magnetic pole layer of a writinghead for a thin film magnetic head;

FIG. 2 is a ternary system diagram showing the compositional range for aCoNiFe layer obtained according to the present invention;

FIG. 3 is a graph showing the relationship between the amount ofsaccharine sodium added and the layer stress of the CoNiFe layer;

FIGS. 4A, 4B and 4C are graphs showing an x-ray diffraction pattern of aCoNiFe layer;

FIG. 5 shows a B—H curve of a CoNiFe layer according to the presentinvention;

FIG. 6 is a cross sectional view of a recording/reproducing separationtype thin film magnetic head using the CoNiFe layer prepared accordingto the present invention to the upper portion of writing head and to aportion of a lower magnetic core; and

FIG. 7 is a perspective view illustrating a structure of a magnetic diskstorage apparatus according to a preferred embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

It is to be understood that the figures and descriptions of the presentinvention have been simplified to illustrate elements that are relevantfor a clear understanding of the present invention, while eliminating,for purposes of clarity, other elements that may be well known. Those ofordinary skill in the art will recognize that other elements aredesirable and/or required in order to implement the present invention.However, because such elements are well known in the art, and becausethey do not facilitate a better understanding of the present invention,a discussion of such elements is not provided herein. The detaileddescription will be provided hereinbelow with reference to the attacheddrawings.

FIG. 1 shows a process flow for a magnetic pole layer of a writing headin a thin film magnetic head in a first exemplary embodiment accordingto the present invention. After preparing a 46NiFe layer 2 on asubstrate 1 in which a reading head is formed, an Ar gas is preferablyintroduced into a sputtering chamber at a degree of attained vacuum ofat least 5×10⁻⁵ Pa, and a CoNiFe layer 3 as a plated underlayer isformed to 100 nm by a DC or RF sputtering method using a CoNiFe alloytarget (FIG. 1A). In this case, a non-magnetic metal may be formed toabout 5 nm as an adhesion layer. A CoNiFe layer 4 is prepared on theunderlayer 3 using a plating solution containing saccharine sodium atapproximately 1.5 g/l as a stress relieving agent under the conditionsshown in Table 1.

In FIG. 1B, a magnetic gap layer 5 is formed thereon. As the magneticgap layer 5, an insulation layer made of materials such as Al₂O₃ or SiO₂is used as a single layer or a lamination layer. On this gap layer 5, aCoNiFe layer 3 as a plated underlayer is preferably formed using asputtering method in the same manner as described above.

A resist frame 7 for forming an upper magnetic core is prepared and,after patterning the same into a predetermined shape, a CoNiFe layer 4and a 46NiFe layer 6 are prepared successively by the plating method(FIG. 1C). While the 46NiFe layer 6 is used to a portion of the upperand lower magnetic poles in this example, the entire portion may beformed by using the CoNiFe layer 4 according to this invention.

TABLE 1 Plating bath temperature 30° C. pH 3.5 Current density 6 mA/cm²Co⁺⁺   5 g/l Ni⁺⁺  15 g/l Fe⁺⁺   2 g/l Saccharine sodium 1.5 g/l

The resist 7 and the underlayer 3 are removed, and a trimming step isthereafter applied for fabricating the upper and lower magnetic cores,each to a predetermined track width.

Exemplary plating conditions are shown in Table 1, and a compositionalrange for preparing a CoNiFe layer is shown in FIG. 2; specifically, 45wt %≦Co≦70 wt %, 10 wt %≦Ni≦25 wt % and 10 wt %≦Fe≦30 wt %, within therange shown in Table 2.

TABLE 2 Plating bath temperature 25–35° C. pH 3.2–4.0 Current density3–12 mA/cm² CO⁺⁺  2–20 g/l Ni⁺⁺  5–30 g/l Fe⁺⁺   1–4 g/l Saccharinesodium 0.5–2.0 g/l

Further, as shown in FIG. 3, when saccharine sodium is added by about0.5 g/l, the stress in the layer can be reduced to about 200 MPa.However, if it is added by 2.5 g/l or more, the stress does not changesubstantially. In addition, since the amount of S in the layer isincreased to deteriorate the corrosion resistance, the addition amountof saccharine sodium is preferably between 0.5 to 2.0 g/l.

FIG. 4 shows an X-ray diffraction pattern of the CoNiFe layer. There areshown: a CoNiFe layer prepared by the sputtering method (FIG. 4A); aCoNiFe layer prepared by the electroplating method on this underlayer(FIG. 4B); and a CoNiFe layer prepared by the conventional method (FIG.4C). For the CoNiFe layer prepared by the sputtering method, only thebody-centered cubic system is observed.

In the CoNiFe plated layer formed on the above-mentioned layer, theface-centered cubic system and the body-centered cubic system areobserved to have a peak intensity ratio: I(200)/I(111)=1.62 andI(110)/I(111)=4.9 when defining the peak intensities for theface-centered cubic fcc (111) face, fcc (200) face and the body-centeredcubic bcc (110) face as I(111), I(200) and I(110) , respectively.Further, when the constitutional ratio is determined by peakdecomposition, the body-centered cubic system is preferably 53% and theface-centered cubic system is 47%. On the contrary, the layer preparedby the conventional method consists almost entirely of the face-centeredcubic system, with little body-centered cubic system observed.

When the peak intensity ratio by the X-ray diffraction is:I(200)/I(111)≧0.5 and I(110)/I(111)≧1, the purpose of this invention maybe attained. Further, when the constitutional ratio for theface-centered cubic system and the body-centered cubic system is40%≦body-centered cubic system≦80% and 20%≦face-centered cubicsystem≦60% providing that the face-centered cubic system+body-centeredcubic system=100, the purpose of this invention may similarly beattained.

FIG. 5 shows a B—H curve for a CoNiFe layer prepared according to atleast one embodiment of the present invention. The magneticcharacteristics of the magnetic layer are such that the saturationmagnetic flux density Bs is 18200 gauss and the coercive force Hch inthe direction of the difficult axis is 0.7 Oe. Referring to Bs, when17500 gauss≦Bs≦20000 gauss and Hch≦1.5 Oe, the purpose of this inventionmay be attained.

FIG. 6 shows a cross sectional view of an exemplaryrecording/reproducing separation type thin film magnetic head using theCoNiFe layer prepared according to the invention for the upper portionof the writing head and a portion of the lower magnetic core. A lowershield layer 9 and a lower magnetic gap layer are formed on anon-magnetic substrate 8, on which an MR or GMR sensor 10 is formed as areading device. After forming a magnetic domain control layer 11 and anelectrode layer 12, an upper magnetic gap layer and an upper magneticshield layer 2 are formed. Further, a magnetic gap layer 5 for thereading device and the writing device is formed, on which a lowermagnetic core is formed.

A 46NiFe layer is formed as the lower magnetic core by the platingmethod. A CoNiFe layer 3 is formed to 100 nm by sputtering, and then aCoNiFe layer 4 is plated to a predetermined thickness by a platingmethod. Successively, the magnetic gap layer was formed. After formingcoils 13 for supplying a recording current and an organic insulatinglayer, another CoNiFe layer 3 is formed to 100 nm by sputtering and aresist frame for forming the upper magnetic core is prepared. AnotherCoNiFe layer 4 and a 46NiFe layer are prepared successively by a platingmethod.

The resist and the underlayer are removed, and, for fabricating both theupper and lower magnetic core to a predetermined track width, a trimmingstep is applied. Further, coils and an organic insulating layer areformed and the 46NiFe layer is frame plated. After fabrication,experiments confirmed that the recording/reproducing separation typethin film magnetic head manufactured as described above showed favorablerecording characteristics and could conduct recording satisfactorily toa high coercive force medium.

FIG. 7 is a perspective view of an exemplary magnetic disk storageapparatus mounting a thin film magnetic head manufactured according tothis invention. The magnetic disk storage apparatus preferably includes:a magnetic disk 15 for recording information; a motor for rotating themagnetic disk 15; an actuator for locating the magnetic head 17 forwriting information to the magnetic disk 15 and reading information fromthe magnetic disk to an aimed position; and a voice coil motor 19.

The storage apparatus may also include a spring attached to the magnetichead for stably keeping the sub-micron space relative to a magnetic disk15 and a guide arm 20 fixed with the spring, which is driven by theactuator and voice coil motor. Further, although not illustrated, theapparatus also comprises a magnetic disk rotation control system, a headpositioning control system and a recording/reproducing signal processingsystem. With the structure described above, a magnetic disk storageapparatus of high recording density may be attained.

Using a magnetic head produced in accordance with the present invention,an intense recording magnetic field may be generated, and a thin filmmagnetic head corresponding to high recording density can be provided.

The foregoing invention has been described in terms of preferredembodiments. However, those skilled, in the art will recognize that manyvariations of such embodiments exist. Such variations are intended to bewithin the scope of the present invention and the appended claims.

Nothing in the above description is meant to limit the present inventionto any specific materials, geometry, or orientation of elements. Manypart/orientation substitutions are contemplated within the scope of thepresent invention and will be apparent to those skilled in the art. Theembodiments described herein were presented by way of example only andshould not be used to limit the scope of the invention.

Although the invention has been described in terms of particularembodiments in an application, one of ordinary skill in the art, inlight of the teachings herein, can generate additional embodiments andmodifications without departing from the spirit of, or exceeding thescope of, the claimed invention. Accordingly, it is understood that thedrawings and the descriptions herein are proffered by way of exampleonly to facilitate comprehension of the invention and should not beconstrued to limit the scope thereof.

1. A method of manufacturing a thin film magnetic head having a lowermagnetic pole, an upper magnetic pole, and a gap layer formed in-betweenthe magnetic poles, comprising the steps of: forming on the gap layer afirst magnetic layer containing Co, Ni and Fe by a sputtering method,and forming a second magnetic layer containing Co, Ni, Fe, andsaccharine sodium on said first magnetic layer, which is as anunderlayer, using an electroplating method as an upper magnetic polelayer, wherein said first magnetic layer is comprised of: 40 wt %≦Co≦70wt %, 10 wt %≦Ni≦25 wt %, and 10 wt %≦Fe≦30 wt %, further wherein saidsecond magnetic layer is comprised of: 40 wt %≦Co≦70 wt %, 10 wt %≦Ni≦25wt %, and 10 wt %≦Fe≦30 wt % and saccharine sodium, said first magneticlayer mainly comprises a body-centered cubic system, further whereinsaid second magnetic layer has a peak intensity ratio ofI(200)/I(111)≧0.5 and I(110)/I(111)≧1, said second magnetic layer has aconstitutional ratio of the face-centered cubic system and thebody-centered cubic system of: 53%≦body-centered cubic system≦80% and20%≦face-centered cubic system≦47%, and said face-centered cubicsystem+body-centered cubic system=100%.
 2. The manufacturing method ofclaim 1, wherein said second magnetic layer is formed from a platingbath containing 0.5 to 2 g/l of saccharine sodium.
 3. The manufacturingmethod of claim 2, wherein said second magnetic layer is formed byconducting electroplating at: a plating bath temperature of from 25° C.to 35° C.; a current density of from 3 to 12 mA/cm²; and a pH value offrom 3.2 to 4.0.
 4. The manufacturing method of claim 1, wherein saidfirst magnetic layer has a saturation magnetic flux density greater thanthe saturation magnetic flux density of said second magnetic layer.